Science 10 – Genetics: DNA, Protein Synthesis & Mutation

Vocabulary flashcards covering DNA structure, protein synthesis steps, and types and causes of mutations.

Nucleus

Organelle that holds the cell’s DNA and directs cell activities

DNA (Deoxyribonucleic Acid)

Double-stranded helix carrying the master instructions for cell function and heredity

Double Helix

Twisted-ladder shape of the DNA molecule

Sugar-Phosphate Backbone

Alternating deoxyribose sugars and phosphates that form the sides of the DNA ladder

Nitrogen Base

One of four molecules (A, T, C, G) that form the rungs of DNA

Adenine (A)

Purine base that pairs with thymine in DNA

Thymine (T)

Pyrimidine base that pairs with adenine in DNA

Cytosine (C)

Pyrimidine base that pairs with guanine in DNA

Guanine (G)

Purine base that pairs with cytosine in DNA

Base-Pairing Rule

A pairs with T, and C pairs with G (Apple–Tree, Car–Garage mnemonic)

Gene

Segment of DNA on a chromosome that codes for a specific protein

Chromatin

DNA wrapped around histone proteins; loosens for gene reading

Histone

Protein spool around which DNA coils to form chromatin

Chromosome

Condensed X-shaped DNA structure visible during cell division; humans have 46

Homologous Chromosomes

Pair of chromosomes (one maternal, one paternal) carrying the same genes

XX

Female sex-chromosome pair in humans

XY

Male sex-chromosome pair in humans

Protein

Molecule made of amino acids that performs structural or functional roles

Structural Protein

Protein that builds body parts such as hair, nails, bones and muscles

Functional Protein

Protein that carries out activities like catalysis, transport or defense

Keratin

Structural protein found in hair, nails, feathers and horns

Actin & Myosin

Muscle proteins responsible for contraction and movement

Hemoglobin

Blood protein that transports oxygen

Antibody

Immune protein that recognizes and neutralizes pathogens

Enzyme

Protein catalyst that speeds up chemical reactions

Protein Synthesis

Two-step process (transcription and translation) that builds proteins from genetic code

Transcription

Copying of DNA code into messenger RNA (mRNA) in the nucleus

mRNA (Messenger RNA)

Single-stranded RNA that carries the genetic code from nucleus to ribosome

Uracil (U)

RNA base that replaces thymine and pairs with adenine

RNA Polymerase

Enzyme that assembles mRNA during transcription

Translation

Decoding mRNA at the ribosome to assemble amino acids into a protein

Ribosome

Cytoplasmic organelle where translation occurs

Codon

Three-base mRNA sequence that specifies one amino acid

Start Codon (AUG)

Codon for methionine that signals beginning of translation

Stop Codon

mRNA codon (UAA, UAG, UGA) that ends translation

tRNA (Transfer RNA)

RNA molecule that carries a specific amino acid to the ribosome

Anticodon

Three-base sequence on tRNA complementary to an mRNA codon

Amino Acid

Building block of proteins; 20 standard types

Golgi Body

Organelle that modifies, packages and ships finished proteins

Mutation

Permanent change in DNA sequence

Chromosomal Mutation

Alteration of entire chromosomes or large segments (deletion, duplication, inversion, translocation)

Gene (Point) Mutation

Change in one or a few bases within a gene (substitution, insertion, deletion)

Frameshift Mutation

Insertion or deletion that shifts the reading frame, drastically altering protein

Positive Mutation

DNA change that increases survival or provides advantage (e.g., HIV resistance)

Negative Mutation

DNA change that harms organism by producing faulty proteins (e.g., sickle-cell anemia)

Neutral Mutation

DNA change with no effect on survival (e.g., spirit bear white fur)

Mutagen

Environmental factor that induces DNA mutations

Carcinogen

Mutagen specifically known to cause cancer (e.g., cigarette smoke, UV radiation)